Many of the early methods of color photography operated by virtue of an additive color screen or color filter element in registration with a suitable silver image. In these methods, a silver image is formed by imagewise exposing a silver halide layer through the screen so as to produce a color image record. The silver halide layer is then developed so as to produce a positive image corresponding to the color image record. This silver image, when viewed in proper registration through the same screen, produces a color reproduction of the original image. This additive photographic process has been used to produce a diffusion transfer transparency material.
Recently, the additive photographic process has been adapted to produce what are called "single-site" color imaging devices. In a device of this type, a color filter element, comprising at least one color array set, is registered with an array of panchromatically sensitive elements in a solid-state imaging device. The solid-state imaging device is generally formed from a silicon wafer. The surface of the wafer is processed to produce a number of arrays of solid-state photosensitive areas sometimes called pixels. By proper selection of the color of each set of color arrays used in the color filter element, a color image can be extracted from a single solid-state device.
Methods of making color filter elements are known. In a typical process, a support is coated with a radiation sensitive dyeable composition such as dichromated gelatin. The resultant layer is then exposed to activating radiation. The element is then washed, preferably with water, to remove the unexposed portions of the layer. The remaining exposed portions of the layer, in the form of stripes, squares or islands in a desired size and shape are then dyed with a suitable dye solution to form a first color array set. This process is repeated to make other differently colored sets of color arrays to form a multicolor filter element. Where there is a problem of dye contamination or dye leaching between the differently colored sets of filter arrays in the element, barrier layers have been provided to separate the sets thereby ameliorating the problem of dye contamination or dye leaching.
Barrier layers formed from photoresist formulation are often used in color filter elements. The problem is that such barrier layers frequently exhibit a visible, yellow color, indicating blue absorption by the layer. Such absorption by the barrier layer is detrimental in solid-state imaging devices which frequently have low blue sensitivity, depending on sensor design.